<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    div {
      width: 100px;
      height: 100px;
      background-color: red;
      position: relative;
      animation-name: example;
      animation-duration: 4s;
      animation-iteration-count: infinite;
      /* 
      动画方向: 
      noramal: (0% -> 25% -> 75% -> 100%) -> (0% -> 25% -> 75% -> 100%) -> ...
      reverse: (100% -> 75% -> 25% -> 0%) -> (100% -> 75% -> 25% -> 0%) -> ....
      alternate: (0% -> 25% -> 75% -> 100% -> 100% -> 75% -> 25% -> 0%) -> (0% -> 25% -> 75% -> 100% -> 100% -> 75% -> 25% -> 0%) -> 
      alternate-reverse: (100% -> 75% -> 25% -> 0% -> 0% -> 25% -> 75% -> 100%) -> (100% -> 75% -> 25% -> 0% -> 0% -> 25% -> 75% -> 100%)
      */
      animation-direction: alternate-reverse;
    }

    @keyframes example {
      0% {
        background-color: red;
        left: 0px;
        top: 0px;
      }

      25% {
        background-color: yellow;
        left: 200px;
        top: 0px;
      }

      50% {
        background-color: blue;
        left: 200px;
        top: 200px;
      }

      75% {
        background-color: green;
        left: 0px;
        top: 200px;
      }

      100% {
        background-color: red;
        left: 0px;
        top: 0px;
      }
    }
  </style>
</head>

<body>
  <div id="box"></div>
</body>

</html>